Lpc2000

Hi Leighton,

Im using the MCB2100 development board from Keil for the time being. 
Our main control unit is in development as we speak...

anyway, the MCB is stuffed with the LPC2129, crystal of 12Mhz.

I have tested my system using YOUR CODE that you pasted below, and I 
agree with my previous answers...the clock WORKS OK at all VPBDiv 
settings....

i print the time to terminal (38400baud) and monitor the time for 
several minutes and it certainly does not run fast (or fast enough 
to visually see anyway!)...

so i am very confused why you see this problem....

so i guess i cannot help any further.... but hope the above helps a 
little....

daft question - are u sure that your PLL is enabled and running?

let me know if you find the solution,
rgds
pete



--- In lpc2000@yahoogroups.com, "Leighton Rowe" <leightonsrowe@y...> 
wrote:
> 
> Thanks for your results
> 
> What lpc are you using by the way? Is your RTC counting at the 
right 
> speed when VPBDIV=0? Try comparing the RTC timers against a normal 
> clock if u can.
> 
> I tried your code on my 12 MHz board (M=5), and this is what I get.
> VPBDIV = 0 so VPB = 15MHz (cclk/4)
> PREINT = 0x000001c8;
> PREFRAC = 0x000061c0;
> RTC runs OK, but it's going twice as fast.
> ....
> VPBDIV = 1 then  VPB = 60MHz (cclk)
> PREINT = 0x00000726;
> PREFRAC = 0x00000700;
> RTC runs OK. Speed is normal.
> ....
> VPBDIV = 2 then  VPB = 30MHz (cclk/2)
> PREINT = 0x00000392;
> PREFRAC = 0x00004380;
> RTC runs OK. Speed is normal.
> 
> For now, It's still unsolved over here.
> 
> Thanks,
> Leighton
> 
> I've included pieces of my code just for reference.
> ************************************
> #define XTAL_FREQ     12000000
> //#define XTAL_FREQ     14745600
> #define MULTIPLIER    5
> //#define MULTIPLIER    4
> #define CCLK          (XTAL_FREQ * MULTIPLIER)      // system 
clock 
> system clock (cclk)
> #define PCLK          (CCLK / 2)
> //#define PCLK          CCLK
> //#define PCLK          (CCLK / 4)
> 
> if(PCLK == CCLK)
> { 
>   VPBDIV = 1;
> }
> else if(PCLK == CCLK/2)
> { 
>   VPBDIV = 2;
> }
> else if(PCLK == CCLK/4)
> { 
>   VPBDIV = 0;
> }
> 
> CCR = AMR = CIIR = ILR = 0;   //clear all RTC Misc registers
> SEC = MIN = HOUR = 0;       //clear timer registers being used
> 
> //Setup Prescalar Values
> PREINT = (PCLK/32768) - 1;               //integer value
> PREFRAC =PCLK - ((PREINT + 1)* 32768);   //fraction value
> 
> CCR |= 2;                         //reset timer
> CCR &= ~2;
> CCR |= 1;                        //start timer
> 
> 
> 
> 
> --- In lpc2000@yahoogroups.com, "Pete" <peterbrown_abroad@y...> 
> wrote:
> > 
> > 
> > ok, got home and have tried on my dev board...
> > Using a 12Mhz crystal, I configured the VPBDiv=0
> > 
> > As a result modified the Fac and Int settings to:
> > PREINT 		= 0x000001c8;//Set RTC prescaler for 
> 12.000Mhz Xtal,
> > 	VBP=15Mhz
> > PREFRAC 	= 0x000061c0;
> > 
> > using the calculations from databook.
> > 
> > I also then had to change my UART settings to match, sicne the 
> PCLK 
> > was now 1/4.....
> > Anyway: ALL WORKS OK. RTC functions normally.
> > 
> > Can you check what values you used for the Prefac/int when you 
> > adjusted the VPBDiv?
> > 
> > Or, since you have it working maybe issue is closed?
> > 
> > anyway, thought i would report my findings!
> > 
> > rgds
> > pete
> > 
> > 
> > So I am confused that you say you had problem with the 
> > 
> > --- In lpc2000@yahoogroups.com, "bty639886" <peter.brown@b...> 
> wrote:
> > > 
> > > when i get home i will check this out on my systsem.
> > > 
> > > I do however have a 12Mhz clock rather than the 14.xx that u 
are 
> > > using. So my preints and facs will be different.
> > > Im suspecting the problem could well be with your prefac being 
0 
> > > given the divider settings...
> > > 
> > > anyway, i will check it out and re-post for future reference.
> > > 
> > > glad you got it working !
> > > rgds
> > > pete
> > > 
> > > 
> > > --- In lpc2000@yahoogroups.com, "Leighton Rowe" 
> > <leightonsrowe@y...> 
> > > wrote:
> > > > 
> > > > > 3. have you tried running with vpbdiv set to 1 (ie 
resulting 
> > in 
> > > > > 60mhz opertion (ish).. i am using that for my system 
without 
> > any 
> > > > > problem...
> > > > 
> > > > Good news!
> > > > 
> > > > After setting VPBDIV = 1 (pclk =cclk) and setting PREINT and 
> > > PREFRAC 
> > > > (based on the user manual), the RTC counted correctly. 
Thanks 
> > > Pete. 
> > > > The RTC also worked for VPBDIV = 2 (pclk = cclk/2).
> > > > 
> > > > But interestingly, the RTC still counted twice as fast after 
> > using 
> > > > VPBDIV = 0. I repeated everything on 2 different lpcs 
(lpc2114 
> > > > @14.7456MHz & lpc2129 @12MHz). You can even try it out on 
your 
> > > own; 
> > > > I wouldn't be surprised you'll get the same results. and got 
> the 
> > > > same results. 
> > > > 
> > > > So RTC's OK only when vpbdiv = 1 (pclk=cclk) or 2 (pclk = 
> > cclk/2). 
> > > > Otherwise RTC's doubles in speed when vpbdiv = 0 (cclk/4). I 
> > hope 
> > > > Philips has an explanation for this one...I have no clue 
why. 
> > > > 
> > > > For now, I can live with using a different vpbdiv setting to 
> > make 
> > > > everything work. 
> > > > 
> > > > Thanks again